1. Field of the Invention
The present invention is related to a pressure controlled switch. More specifically, the present invention is directed to a differential pressure responsive switch.
2. Description of the Prior Art
Pressure controlled switches are well-known in the art. However, if such conventional switches are used for monitoring a low pressure, a relatively large area diaphragm is required for generating the necessary switching force. Furthermore, an exact adjustment of such low pressure switches and the maintenance of such an adjustment over a long period of time is difficult because of the low pressure whereby small changes of the diaphragm properties, e.g., resulting from aging, or mechanical hysteresis in the switch operating mechanism, lead to undesirable changes in the response of the switch. Accordingly, it is desirable to provide a pressure switch which overcomes the aforesaid problems when being used to monitor low pressures.